Fluid pressure tool



Aug. 16, 1932. E w. STEVENS FLUID PRESSURE TOOL 'Filed March 30, 1951 I N VEN TOR. Edward W. Stevens A TTORNE Y.

pocket at the rear end of Patented Aug. 16, 1932 UNITED STATES PATENT OFFICE EDWARD W. STEVENS, OF DETROIT, MIC HIGAN, ASSIGNOR TO CHICAGO PNEUMATIL TOOL COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY nun: ranssuan TOOL Application filed March 30, 1931.

This invention relates to fluid pressure tools, especially percussive tools, with particular re'ference to the mechanism for controlling the fluid supply and the structural arrangement at the rear end of the piston chamber. It is particularly adapted to portable pneumatic tie tamping tools but can be used to advantage on other 'portable tools of a similar character.

()ne object of the invention is to improve the structure and the throttle mechanism of a fluid pressure tool. Another object is to provide a throttle handle arranged for convenient control of the motive fluid and in which the throttle mechanismis adequately protected from injur Another object is to prevent injury to the tool in the event that the piston should overrun on its back stroke. Another object is to provide a compression the piston chamber or storing motive fluid for the forward or working stroke of the piston. Still other objects Wlll be apparent from the detailed description which follows.

In order to illustrate the invention one concrete embodiment thereof is shown in the accompanying drawing, in which:

1g. 1 is a side elevational view largely in section;

' Fig. 2 is a top plan view; and

Fig. 3 a fragmentary vertical sectional view at an angle of 90 to Fig. 1, substan.- tially on the line 3 3 of Fig. 2.

In the embodiment of the invention chosen for the purpose of illustration, the percussive motor comprises a cylinder 4 providing a differential piston chamber within which reciprocates a hammer piston 5 for imparting blows'to a tamper bar, drill steel, or other working tool 6 extending into the forward end of the piston chamberand retained in operative" position by suitable means (not shown) in a front head 7 which issecured to cylinder 4 in any suitable manner as by bolts 8. The percussive motor may be of any suitable or desired type, either valved or valveless. In the present instance it is illustrated as a valveless tool with the motive fluid constantly passing (when the throttle valve is open) through passage 4a to cylinder 4: be:

Serial in. 526,189.

neath shoulder 5a on the piston. This constant pressure will drive the piston rearwardly from the position shown in Figs. 1 and 2 since the rear or upper end of the piston chamber is in communication with exhaust ports 4?; by axial bores 56 and radial ports 1n the piston. As the piston moves rearward-.

1y, ports 50 pass out of register with exhaust ports 4]; and eventually register with passage 4a whereupon motive fluid passes to the rear end of the piston chamber and the piston is then driven on its forward stroke by the predominating pressure thus produced in a manner well known to thoseskilled in the art.

The manual control mechanism for the tool is entirely contained within a back head or handle 9 secured to the rear or upper end of cylinder 4 in any suitable or' desired manner as by a series of bolts 10. A thick gasket 11 of stiff but somewhat flexible material such as fibre is preferably interposed between cylinder 4 and handle 9 and has an aperture therethrough for a purpose presently to be described. The sides of the aperture may be protected by a grommet 12. Handle 9 has a bore 9a in axial alignment with the pi on chamber and this bore is suitably divided'mto two chambers 13 and 14. Chamber 13 communicates at all times with the piston chamber by reason of the aperture in gasket 11 while chamber 14 is divided ofi' from chamber 13 by a commumcation with the piston chamber. Chamber 14 may be supplied with pressure fluid from the supply pipe S secured by a conventional nipple in a threaded opening 15. Handle 9 shows two such openings 15 on op partition 15 and is normally out of posite sides thereof and the'opening on the I reverse side to hose connection S is closed by plug 16. The extent of live air chamber 14 is restricted by a throttle tube 17 suitably secured in bore 9a,

the bore of tube 17. The enlarged by a counterbore as with a press fit, and the lower end of the tube provides a seat for which has a stem 18a slidseat to provide a chamber" ket 11. A spring 20 in live air chamber 14, interposed between partition 15 and throttle valve 18 yieldingly maintains the latter on its seat. In order to make the back head or handle 9 a complete and independent control unit, the bore 9a is enlarged below chamber 14 and adjacent the piston chamber by a coun-' terbore 9b in which is secured, as by threaded connection, a cup shaped retainer member 15a, the base of which forms partition 15 and the hollow interior of which provides chamber 13.

Manual control of the throttle valve is obtained by a cam lever 21 pivotally mounted on a transverselyextending pin 22 in line with stem 18a (Figs. 1 and 2) and spanning an arcuate slot 90 in which the cam portion of lever 21 is mounted for operative engagement with the end of stem 18a. Control lever 21 is shown in full lines in Fig. 1 in closed throttle position and in dotted outline in the same figure in open throttle position. Indents 21a and 216 are indicated in Fig. 1 in the cam portion of lever 21 to be engaged by plunger 23 backed by spring 24 (Fig. 2) in handle .9 for yieldingly retaining lever 21 in throttle closed and throttle open positions respectively. In the form shown, handle or back head 9 is of T shape with transversely aligned grip portions 911 on opposite sides of the vertical axis of the tool. The projection of control lever 21 out of the milled recess 90 is just suflicient to permit it to be moved from one position to the other by the thumb of the operator without requiring him to remove his hand from the adjacent grip portion 9d.

The control and operation of the tool will be obvious. With the parts shown in full outline in Fig. 1, the throttle valve is closed. To put the tool into operation, the operator flips lever 21 with his thumb from the closed positlon shown in full lines to the open position shown in dotted lines in the same figure,

plunger 23 being forced out of engagement with recess 21a and snapping into recess 21?) to hold lever 21 in the open position. With throttle valve 18 thus forced off its seat by the cam portion of t-heoperating lever, the live motive fluid passes from chamber 1 1 into chamber 19 and thence by passage 19a and passage 4a to the piston chamber where it reciprocates piston 5. A reverse flip of cam lever 21 will permit valve 18 to return to its seat under the action of spring 20.

From the above it will be apparent that the present invention provides a back head or handle construction with entirely self-contained throttle control mechanism, that the axial bore in the back bead provides both a live air chamber for the pressure fluidand a compression chamber or pocket at the rear end of the piston chamber, that the cup shaped retainer 15a performs three functions since it acts as a spring stop, seals or divides til live air chamber from the compression pocket, and forms the compression pocket for storing air for the forgvard stroke ofthe piston, that gasket 11 forms a seal between the cylinder and the back head or handle member and acts as a butter should the piston in its rearward travel overrun and strike, and that the throttle mechanism and its operating lever are shrouded and enclosed to such an extent as to protect them from damage and from accidental displacement.

While the invention has been herein disclosed in What is now considered to be a preferred form, it is to be understood that the invention is not limited to the specific details thereof but covers all changes, modifications, and adaptations within the scope of the appended claims.

I claim as my invention:

1. In a fluid percussive tool, in combination, a cylinder, a piston reciprocable therein, ahandle secured to said cylinder and,

having a bore in axial alignment with said cylinder, and a resilient member interposed between said cylinder and said handle and having an aperture therethrough for establishing communication between said piston chamber and said handle bore.

2. In a fluid pressure percussive tool, in combination, a cylinder, a piston-reciprocable therein, a handle secured to said cylinder and having a bore in axial alignment with said cylinder. a resilient member interposed between said cylinder and said handle and having an aperture therethrough for establishing communication between said and piston chamber and said handle bore, throttle mechanism for the pressure fluid supply mounted in said bore but out of axial communication with said piston chamber.

3. In a fluid pressure percussive tool, in combination, a cylinder, a piston reciprocable therein, a handle secured to said cylinder and having a bore in axial alignment with said cylinder, a resilient member interposed between said cylinder and said handle and having an aperture therethrough for establishing communication between said piston chamber and said handle bore, a partit-ion across said bore in spaced relation to said member, and control means for the pressure fluid supply in said bore beyond said partition.

4. In a fluid pressure percussive tool, in combination, a cylinder, a piston reciprocable therein, a handle secured to said cylinderv and having a bore in axial alignment with said cylinder and enlarged by a counterbore adjacent said cylinder, a throttle tube in said bore providing a'seat, a throttle valve cooperating with said seat and having a stem slidably received in said tube, a spring for maintaining said valve on its seat, and a partition member see red in said counterbore to .provide an abutm nt for said spring and to divide the handle bore into a live air chamber adjacent said valve and a compression chamber adjacent said cylinder, and means establishing constant communication between said compression chamber and the piston chamber.

5. In a fluid pressure percussive tool, in combination, a cylinder, a piston reciprocable therein, a handle der and having a bore in axial alignment with said cylinder and enlarged by a counterbore adjacent said cylinder, a throttle tube in said bore providing a seat, a throttle valve cooperating with said seat and having a stem slidably received in said tube, a spring for maintaining said valve on its seat, and a partition member secured in said counterbore to provide an abutment for said spring and to divide the handle bore into a live air chamber adjacent said valve and a compression chamber adjacent said cylin-. der, and a buffer member for said piston sealing the joint between said cylinder and said handle and having an aperture establishing connection between said compression chamber and said piston chamber.

6. A combined back head and handle unit for the cylinder of a fluid pressure tool, said unit having a bore arranged to align with the cylinder, a partition in said bore dividing the same into a compression chamber for constant communication with the interiorof the cylinder and a live air chamber, a throttle tube in said bore for limiting the extent of said live air chamber and providing a valve seat therein, a throttle valve having a stem slidably received in said tube, and a spring interposed between said valve and said parpartition to provid tition for yieldingly maintaining the former in en agement with said seat.

7. combined back head and handle unit for the cylinder of a fluid pressure tool, said unit having a bore arranged to align with the cylinder and having a counterbore at its lower end, a cup shaped member secured in said counterbore in an inverted position to provide a partition in spaced relation to said cylinder, the interior of said member forming a compression chamber for communication with the'interior of the cylinder, a throttle tube in said bore inspaced relation to said e a separate live air chamer, a throttle valve movably mounted in said tube for controlling the outlet from said live air chamber, and a spring interposed between said valve and said partition.

8. A combined back head and handle unit for the cylinder of a fluid pressure tool, said unit having a bore arranged to align with the cylinder, a partition in said bore dividing the same into a compression chamber for constant communication with the interior of the cylinder and a live air chamber, a throttle tube in said bore for limiting the extent of said live air chamber and providing a valve secured to said cylinseat therein, a throttle valve having a stem slidably received insaid tube, a s ring interposed between said valve and sa d partition for yieldingly maintaining the former in engagement with said seat, and control.

{)neans for said valve at the outer end of said ore.

9. A combined back head and handle unit for the cylinder of a fluid pressure tool, said unit having a bore arranged toalign with the cylinder, a partition in said bore dividing the same into a compression chamber for constant communication with the interior of the cylinder and a live air chamber, a throttle tube in said bore for limiting the extent of said live air chamber and providing a valve seat therein, a throttle valve having a stem slidably received in said tube, a spring interposed bet-ween said valve and said partition for yieldingly maintaining the former in engagement with said seat, and a control lever having a cam in operative engagement w th said valve stem, said lever bein pivot ally mountedat the outer end of said bore.

10. A combined back head and T-handle unit for a fluid pressure percussive tool, said unit having an axial bore, means for connecting a supply conduit for communication with said bore, throttle mechanism mounted in said bore, and a control lever for said mechanism mounted between the grip portion of said handle and having only slight projection thereabove for lateral movement between open and closed positions.

11. A combined back head and T-handle unit for a fluid pressure percussive tool, said unit having an axial bore, means for con-' necting a supply conduit for communication with said bore, throttle mechanism mounted in said bore, and a control lever of the cam type pivotally mounted between the grip portions of said handle for movement in the plane thereon, the cam portion of the lever being completely shrouded and the lever having only handle.

12. A combined back head and T- handleunit for a fluid pressure percussive tool said unit having an axial bore, means for connecting a supply conduit for communication with said bore, throttle mechanism mounted in said bore, and a control lever of the cam.type pivotally mounted between the grip portions of said handle for movement in the plane thereon, the cam lever being .completely shrouded in an arcuate recess at the top of said bore.

13. A combined back head and T- handle unit for a fluid pressure percussive tool, said unit having an axial bore, means for connecting a supply conduit for communication with said bore, throttle mechanism mounted in said bore, a control lever of the cam type pivotally mounted between the grip portions of said handle for movement in the slight projection above said portion of the planethereon, the cam portion of the lever being completely shrouded in an arcuate recess at the top of said bore, and means for releasably holding said lever in at least one of its control positions.

Signed by me at Detroit, in the county of Wayne and State of Michigan, this 27th day of March, 1931.

EDWVARD W. STEVENS. 

